Lopi liberty. Stove pipe temps vs stove top temps

[kversch]

ithis is my second season with this stove..

So my pipe temps seem to be running around 800-850 well my stove top temps are around 650-700 with the blower on almost full.. are these pipe temps something to be worried about. I know this stove like to run hot and hard. Seeems to be hotter then most other similar stoves. But I get nervous when the stack are that hot on the probe thermometer. I can remember having the same results las twitter at times especially when it was colder out. Tonight's load was mostly sugarmaple with one decent size split of black locust and a couple cherry splits. everything was average medium sized splits.

I'm really working to try to fine tune my stove operation this season.

 

[begreen]

Flue temps seem high. Is this with the air closed all the way down? Are those surface temps on single-wall stove pipe or probe temps in double-wall pipe?

 

[Chimney Smoke]

I don't have the exact same stove but on my Lopi I never have temps that high. My stovetop usually gets up to around 650 on a full load of hardwood and my flue temps with a probe thermometer doesn't get any higher than around 600-650. The flue usually cruises around 450-500.

 

[BradleyW]

Yikes. I second begreen's questions. Also, what does the fire look like? Is the entire box engulfed in flame or do you have mostly secondary burning?

 

[kversch]

Flue temps seem high. Is this with the air closed all the way down? Are those surface temps on single-wall stove pipe or probe temps in double-wall pipe?

Air was closed down I would say 98%. All that was left was just a tinkly pull to close it all the way down. The temps are off the probe thermometer with double wall pipe. And stove top temps were read with my laser heat gun.

Yikes. I second begreen's questions. Also, what does the fire look like? Is the entire box engulfed in flame or do you have mostly secondary burning?

The fire was mostly secondary's burning like jet engines, I can seem to get the lazy secondary's with full loads.

 

[BradleyW]

I wonder if your thermometer is malfunctioning.

 

[begreen]

First thing to do is the dollar bill test on the stove door gasket. Try at several points around the door. Also, make sure the bypass is closing completely and that the baffle bricks are seated correctly in place.

Was this on a cold start or with a reload on a hot coal bed? Are the splits nice and thick (5-8") or on the smaller side?

 

[kversch]

First thing to do is the dollar bill test on the stove door gasket. Try at several points around the door. Also, make sure the bypass is closing completely and that the baffle bricks are seated correctly in place.

Was this on a cold start or with a reload on a hot coal bed? Are the splits nice and thick (5-8") or on the smaller side?

The bypass seems to be closing fully and the baffle bricks also look to be in the right place. I will have to let the stove cool when temps warm up to get a better look as well as try the dollar bill test.

It was not a cold start it was on a bed of coals, I try t do my reloads at stove top temps or 300-350. Pull and remaking coal forward and let them get hot again. Befor filling the stove.

The splits were a mix a few big thick ones and some on the smaller side. Depending on the coal bed and splits I can normally get between 8-10 splits in the box with a mix of n/s e/w loading.

Last nights load went much smoother, Same wood minus the black locust, all sugar maple. Outside temps were a bit warmer high 20's instead of low 20's high teens.



On a side note. How often do you have to clean your ash out? It seems like I can go 3-4 days befor a hot clean out.

 

[Woody Stover]

minus the black locust

Yep, once that BL finally gets rolling it's hard to slow it down. I definitely need a lower air setting on a load of that stuff.

 

[Highbeam]

Supposedly, the chimney system is rated for 1000 degrees continuous so you are below redline. Non-cats dump tons of unregulated, full throttle, secondary combustion air into the firebox above the fire for cleaner emissions and since your wood was putting out lots of smoke, the stove was doing its job by burning it regardless of what you as the operator desire. What you really need to worry about is that secondary burn boiling even more smoke out of the wood which causes even more secondary fire which spirals into a runaway.

I do not like operating a stove that does not cool when you shut the air control fully. I've been in runaway situations and it's not fun to just wait it out.

 

[lopiliberty]

I'm finishing a section of maple in my stack and I have to be extremely careful of run away fires. I have had the stove top glowing this year with a full load of maple. I found if I keep a lot of ash in the stove burn the coal bed down to where there is almost no coals left and shut down the air fairly quick I have better control. Most of the time the secondary's go out but they always reappear 20 minutes later. Most of the time I will have control but sometimes I have to break out the tinfoil to cover the holes. Don't know what it is about maple but when I decides to go IT GOES!!

 

[Sprinter]

I don't have the exact same stove but on my Lopi I never have temps that high. My stovetop usually gets up to around 650 on a full load of hardwood and my flue temps with a probe thermometer doesn't get any higher than around 600-650. The flue usually cruises around 450-500.

I'm quoting this because his scenario seems more normal. A flue temp of 850 is not dangerous, but quite wasteful if it goes on, although I see it sometimes if I'm not attentive to a new start.

If your splits are on the small side and quite dry, that could be making it worse. Also, mixing N-S and E-W may contribute to excessive off-gassing on a hot reload. If you put too much wood on a large, hot coal bed, that can cause a fire that is hard to control, even runaway.

I'm just throwing some stuff out there. It's hard to tell what you may be experiencing.

 

[kversch]

Did the dollar bill test last night well the stove was coolish. On the latch side of the door seemed ok. Could pull the bill out with some effort but not supper easy same with the hinge side. The bottom of the door felt good seemed to pull out a bit harder but could have just been having to pull against the door and not straight down. The top of the door seemed to pull out much easier the any other part of the door still some resistance but not as much as other spots.

I'm finishing a section of maple in my stack and I have to be extremely careful of run away fires. I have had the stove top glowing this year with a full load of maple. I found if I keep a lot of ash in the stove burn the coal bed down to where there is almost no coals left and shut down the air fairly quick I have better control. Most of the time the secondary's go out but they always reappear 20 minutes later. Most of the time I will have control but sometimes I have to break out the tinfoil to cover the holes. Don't know what it is about maple but when I decides to go IT GOES!!

So instead of letting the wood get a decent char befor really cutting the air back all the way should I just cut it back much quicker? Normally I try to let the stove top temps work there way up to 500 befor cutting the air all the way in.

 

[fespo]

I have the same stove. same problem. I have tried everything you can think of. I have a tall flue, it can suck the horns of a Billy Goat. I put in a flue damper, the colder it is the more I close the damper. It did not solve the flue temps but helps contol the fire on real cold night.

 

[Chimney Smoke]

So instead of letting the wood get a decent char befor really cutting the air back all the way should I just cut it back much quicker? Normally I try to let the stove top temps work there way up to 500 befor cutting the air all the way in.

Holy cow, I think if I let my stove top get to 500 before shutting down the air it was sound like a jet engine on full afterburner. On a typical reload of ~250 degrees stove top I close the door and open my air all the way. Usually within 10 minutes (depending on the coal bed) I'm closing my air half way and my flue is around 350-400. Another 5 minutes and my air is 75% closed with the flue around 500 and the secondaries roaring. Another few minutes and a final tweak of the air and it's settled right in for a few hours. I also don't have a perfect setup with a through the wall install and no chase, 18 foot chimney with two 90's between the stove and chimney.

 

[lopiliberty]

So instead of letting the wood get a decent char befor really cutting the air back all the way should I just cut it back much quicker? Normally I try to let the stove top temps work there way up to 500 befor cutting the air all the way in.

There's really no right or wrong answer to this question. Sometimes you have to go by what's going on inside the stove and forget about the stove top temps. If you do cut the air back sooner keep and eye on it and make sure the secondary's do kick in and it doesn't turn into a smoldering mess

 

[begreen]

I watch flue temp now more than stove top. Waiting for the stove top to reach 500F can mean a 1000º+ flue temperature.

 

[Highbeam]

I watch flue temp now more than stove top. Waiting for the stove top to reach 500F can mean a 1000º+ flue temperature.

I totally agree with this and experience it as well. I quickly overfire the flue long before the stove reaches anything close to the desired temperature.

With dry wood, the fire can quickly be releasing plumes of fuel which will ignite into primary and secondary combustion and start to heat the thick walls of the stove but the thin walls flue system rapidly gain temperature.

 

[MagKarl]

If you are getting 8-10 splits in with a mix of N-S and E-W loading, I'm going to say you're splitting your wood way too small. The more surface area of wood to burn/outgas, the more it wants to go nuclear on you.

I'd also suggest you cut back the air much sooner.

 

[Sprinter]

With dry wood, the fire can quickly be releasing plumes of fuel which will ignite into primary and secondary combustion and start to heat the thick walls of the stove but the thin walls flue system rapidly gain temperature.

That's exactly what happens. I haven't really thought about it, but I also have been watching flue temps most closely. If I had to choose between a stove top and a flue thermometer, I'd have to choose the flue one. But I would probably cheat with my IR gun a lot.

 

[kversch]

I run a n/s e/w load to be able to fill the wood box up full. My splits run 16-18 inches long. I only end up with 2 medium and sometimes a small 3rd going in n/s.

Do you think I would be better off just collecting all the shorter stuff and running a full n/s load when I can and not run the mix n/s e/w load?



Split size? So for this stove I want much larger splits? The stove shop told me when we got the stove not to use the big "over nighters" that your grandpa would use. So I've been splitting down my stuff a bit smaller then I would have. If that's the case it's going to suck for then next 2-3 years with amaller splits.

 

[Chimney Smoke]

My firebox is something like 2.2 cubic feet. On a small coal bed I can usually put 5-7 splits in and it's fully loaded. My splits are usually no bigger than 5 to 6 inches on any one side.

 

[Highbeam]

Split size? So for this stove I want much larger splits? The stove shop told me when we got the stove not to use the big "over nighters" that your grandpa would use. So I've been splitting down my stuff a bit smaller then I would have.

So the stove shop is selling lots of these modern EPA stoves to people that have lots of experience with the smoke dragons. The EPA stoves need dry wood to operate as designed. Old timers don't know what dry wood is so to minimize complaints, the stove shop is playing it safe by telling you to use small splits which makes burning wet wood more enjoyable. You can use large splits,5-6 inches on the largest dimension, successfully IF that wood is dried to under 20%.

Both of my stoves have a flue temp meter and a stove top meter. I really think you need both to run a stove properly even though I'm sure there are those that just wing it.

 

[Sprinter]

If you are getting 8-10 splits in with a mix of N-S and E-W loading, I'm going to say you're splitting your wood way too small. The more surface area of wood to burn/outgas, the more it wants to go nuclear on you.

I'd also suggest you cut back the air much sooner.

The most important factor to watch for in any new fire is that the secondaries are burning. That takes only about 1100F in the box. Depending on the stove, that can happen at as little as 200F on the stove top (for my stove anyway). So you have to monitor the behavior of fire and also chimney output. The best single indication is when the smoke stops emitting from the chimney. At that point, the flue temp should be in a safe and functional temperature.

Then you can start to turn the air down while monitoring the fire. Keep turning it down as long as the secondaries are burning.

The others are right that the more wood surface area you have, the more fuel (the gasses and smoke) will be feeding the fire, and sometimes the stove just can't dissipate it fast enough. You need to find a way to minimize that. Unfortunately, criss-crossing the pieces can encourage that process.

If you are reloading a lot of smallish wood on a hot bed of coals, as you suggested you do, that can be a recipe for an overfire depending on how much and how hot the coals are. Again, because the stove can't dissipate the kind of heat released so suddenly. You may want to watch the reloading process.

The other thing I noticed is your question about ash removal. If your stove has an ash drawer with a dump, these very often get stuck partly open, feeding too much primary air. That can be a common problem leading to your symptoms. Just a thought.

 

[kversch]

I hint there might be some confusion when I saw I'm doing a combo N/S E/W load. It's not in a criss cross or log cabin style. It's more like this

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My splits may be a bit on the small side. So hopefully I can get in to sone bigger ones soon.